Locating underground lawn sprinkler pipes

I have need to place a wire underground to service a lamp post in a back yard. The problem is that there is a lawn sprinkler system in this yard and the homeowner has no idea how the pipes run. She did turn on the sprinklers, but that only shows me where they are located. This 45-50 foot ditch will be hand dug, the lady does not won't a trenching machine in her yard. But, somewhere I will most likely cross one, or more, of the sprinkler pipes. The local utilities locating company says they do not locate sprinkler pipes for individual contractors, just the big utility contractors. The local rental place does not have a locater to rent for this. I am not experienced with "Dowser Rods" either. Does anyone have a suggestion as to how to find/locate these sprinkler pipes? Thanks, David

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Locating underground lawn sprinkler pipes

I would not worry about it if you are hand digging the trench you will know when you find one.

But if you must find them remove one of the sprinkler heads that you think will have a line that will cross the trench. Then run a copper wire through the head down the pipe. Get a metal detector from the rental place and run the metal detector over the area you want to trench. Teh wire inside the pipe will show up. Hand dig in that area and whammy pipe found.

Post if you want more info on how this is done.

Big Nate

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Locating underground lawn sprinkler pipes

Just a thought, but most intelligently installed sprinkler systems run a main line down the middle of a yard, then Tee off of that to the individual heads from what i've been told.. Thats not to say your system was done like that, I know mine wasnt. If your hand digging, you shouldnt have much of a problem, I dont think your going to break a sprinkler pipe even if you hit one directly. Theyre pretty tough, but if you get a patch of dirt that just WONT pull up as easy as the rest of it did, you might be next to a pipe, so back the shovel out an inch or two and try again.

Big N8, Thats friggin brilliant.... I never thought of doing it that way... Only problem with it is that some sprinkler systems have thoes stupid fittings that have like a 90* in them where they attach to the pipe, I know mine does.... But still.. Thats a pretty clever idea..

Locating underground lawn sprinkler pipes

Often a sprinkler head near its supply pipe is also attached to a pipe about a foot long that is in turn tee'd into the supply line. This makes it easier to get the head at the right level when the supply pipe might be a little high or low in the trench.

A "main line" supply pipe out in the lawn will likely serve only about four heads. Additional main supply pipes for additional heads usually do not run in the same trench down the middle of the lawn with long lateral pipes to reach the various heads.

In the event a main line does serve many more than four heads, there will be (electrically operated) valves buried along the line here and there in the lawn with access covers, and with wires buried accompanying it.

I was going to suggest turning the sprinklers on, (putting trash cans over the ones nearest you) and using a stethoscope to listen to the ground starting near a head and working your way back to the house. I have not tried it.

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Locating underground lawn sprinkler pipes

Just go ahead and hand dig.

Be prepared to patch up some PVC if you break one, easy enough to fix. I have twelve valves and a bunch of pipe run every which way by differenet folks over the years. I break one now and then when moving a rose bush or other minor escavation.

Locating underground lawn sprinkler pipes

Sprinkler pipes are magical ...
They instantly appear exactly where you want to dig.

My wife once found a pipe by driving a single bean-pole into the ground at a random location in the middle of the yard.

Since then, I've tried to keep a running map of pipes as I find them. You may not know exactly where each pipe is running but you can infer some data by looking inside your valves to see which direction the mains are running.

Also, as you replace each sprinkler head (which will happen eventually) you can dig out just a little more around the head than you need and see which way the pipes are running.

And of course each time you hit a line, jot down the direction it was running, after you fix it.

All thoughtful homeowners keep a small supply of couplers, tees, caps, pipe & glue in the garage to make quick repairs. For jobs like trenching, just go to town and plan on making a repair.

Locating underground lawn sprinkler pipes

Maybe you can get the power company or call around to see if anyone has one of those air powered deals that dig under the ground to cary wires without having to dig a trench . it works like a snake that can be steered using compressed air . sorry for the vague info but they used one at my old house to run powerline underground .